Process of obtaining alumina.



3 cheaper method of obta V UNITE STATES PATENT OFFICE.

MATHEW? ROTHBERG, or JOHNSTOWN, PENNSYLVANIA.

PROCESS OF OBTAINING ALUMINA.

SPECIFICATION forming part of Letters Patent No. 657,453, datedSeptemberl, 1900.

Application filed March 5, 1900.

T0 aZZ whom it may concern:

Be it known that I, MATHEW E. ROIHBERG, a citizen of the United States,and a resident of Johnstown, in the county of Gambria and State ofPennsylvania, have invented certain new and useful Improvements inProcesses of Manufacturing Alumina; and I do declare the following to bea full, clear, and exact description of the invention, such as Willenable others skilled in the art to which it appertain to make and usethe same.

The invention has relation to the manufac ture of alumina, (Al O and itconsis the novel process hereinafter set forth; In carrying out thisprocess I desire pensive, as it has been pra from the mineral bauxitcostly process. 'Furtherm found in a limited num he ..fii erialwhich Iuse in carbes clay, shale, or simialumina is a constituent. y? tf atedwith sulphuric acid in any of the Vi gil-known methods by which thealumina clgontained in it is changed to alumina sulphate, and thissulphate is leached out with water. The aqueous solution of alumina sulphate thus obtained is what I use in 'thefirst step of my process; butImay use -alu mina sulphate obtained in any other manner orfromf=anyother source. The aluminasulphate solution is brought intosuitable tanks or v essels, and to it is added about an equal quaqntityof lime chloride, eitherdryor,

admiX tu'r brings about a reaction, the resuit-ant: od'ucts of which areinsoluble lime su'lphatje gwhich settles off, and alumina chloha ch;being soluble, remains in .the clea iiqu 3 From thisalumina-chlorideliqbt pure alumina by treating it with '6 either in theform ofmilk of lime solid form. The lime sulphate rlred to as aresultant of the reac- This Serial Ila. 7,407- (No specimens.)

tion with lime chloride is available for the production of superiorplaster of-paris. This is effected by suitably filtering it from theclear alumina-chloride solution, washing and drying, and, finally,calcining it at a regulated temperature. The abovedcscribed reactionbetween alumina sulphate and calcium chloride is usually not quitecomplete, a slight proportion of lime sulphate being soluble in thealumina-chloride liquor. In jordertopurify the liquor from the residualhate after the solid lime sulphate has n separated, I add to the liquora small quantity of barium chloride, either solid or dissolved in water,in such amount as will precipitate all of the remaining sulphate in theliquor and in addition leave dissolved in the alumina-chloride liquor aslight excess of barium chloride, which does not interfere with thesubsequent use of the liquor. On the other hand, the presence of anylime sulphate in the aluminous liquor is injurious. The barium sulphateis now filtered off and is found after suitable washing treatment to bea very fine grade known ln the arts as precipitated baryta andextensively used. To the purified solution of alumina chloride is addedquicklime, either dry or in the form of milk of lime, as may be mostconvenient. The reaction between the lime and the alumina chloridecauses the alumina to be precipitated from the solution and the lime togo into the solution in its place as lime chloride. This precipitatedalumina is found to be after separation from the limechloride liquor byany common method of filtration and after suitable washing andcalcination a very superior article for the man ufacture of metallicaluminum and for use in the arts where a pure alumina is required. Thelime-chloride liquor remaining after the separation of the alumina is,as a final step in the process, returned to the tank used in the firststep and is then again combined with a fresh portion of alumina sulphatefor the precipitation of lime sulphate, as before. There is thus no lossof lime chloride, as it is used over and over for action ofprecipitation Having described this invention, what I claim, and desireto secure by Letters Patent, is

in fresh portions of alumina-sulphate liquor.

1. The process of manufacturing alumina, which consistsiiu' iiixingli'm' euidfiue with a solution of aldminasulphate', subsequently addinglime to the alumina-chloride solution produced thereby, and finallyseparating and heating the resultant tially as specified-. l

2. The process of manufacturing alumina,

which consists in mixing, lime chloride with a solution of aluminasulphate, treating the rium chloride, adding lime to the aluminachloridsolutiofi'sotreated and finally sees-=- rating and. heating theresultant precipitate, substantially as specified. l

* 3... The process of simultaneously manufacg turing plaster-of-paris,alumina andbaryta,

p i e t na w t 1 r thirdly,addinglime-totlie purified alumina,

which eou'sistsin first mixing together solutioiis'li'f a uminasulfilififfiiaiid lime chloride, and se arating out The" "resultant limesulphate; secondly, treating the resultant alumina-chloridesolution'w'ith barium chloride, and separating out the barium sulphate;

chloride liquor, separating and heating out the resultantpreoipitate,and fourthly recov- 'r'ing the liine cliloride-s'olution, substantiallyresultant aluminachloride solution with baas specified.

In testirnony whereof I affix my signature MATHEW E. ROTHBERG.Witnesses: i

' JOHN BROWN,

Eow. 'LEVEEGOOD.

